JP7683573B2 - High pressure tank mold structure - Google Patents

Description

The present invention relates to a mold structure for a high-pressure tank.

A known high-pressure tank to be mounted on a fuel cell vehicle or the like is one that includes a liner having a cylindrical body and a pair of dome sections provided at both axial ends of the body, and a fiber-reinforced resin layer that covers the outer surface of the liner. High-pressure tanks with this structure are manufactured by the FW (filament winding) method. In the FW method, a liner is first formed, and then the formed liner is used as a winding core to wind a resin-impregnated fiber bundle around the outer surface of the liner multiple times, or the fiber bundle is impregnated with resin and wound around the outer surface of the liner multiple times.

Recently, a method for manufacturing a high-pressure tank using the RTM (Resin Transfer Molding) method has been developed. That is, a preform (also called an intermediate body) in which a fiber bundle is wound around the outer peripheral surface of a liner is placed in a mold, and then uncured resin having fluidity is injected into the mold, and the resin is impregnated into the fiber bundle of the preform and cured to manufacture a high-pressure tank. And as for a mold used in the RTM method (hereinafter referred to as an "RTM molding mold"), for example, one having a base mold and a nested mold that fits in the center of the base mold, as described in the following Patent Document 1, can be mentioned.

Special Publication No. 6-98648

High-pressure tanks vary in diameter and length due to the space required for installation in a vehicle and the amount of gas carried, so preforms with various shapes are required. In addition, in the case of RTM molding dies, the molding conditions for thoroughly impregnating the resin into the preform, which is made by winding a thick fiber bundle, are strict, and many structures are required to achieve these molding conditions. Therefore, simply replacing the nested die that contains the preform makes it difficult to accurately fill and impregnate the resin, which can lead to a decrease in the quality of the manufactured high-pressure tank. It is possible to prepare RTM molding dies for each preform shape in order to ensure quality, but this creates a new problem of increased manufacturing costs.

The present invention has been made to solve these technical problems, and aims to provide a mold structure for high-pressure tanks that can manufacture high-quality high-pressure tanks at low cost.

The mold structure for a high-pressure tank according to the present invention is a mold structure for a high-pressure tank for accommodating a preform having a fiber bundle wound around the outer peripheral surface of a liner and impregnating the fiber bundle of the preform with resin, and is characterized in that it is equipped with a main body having an upper mold and a lower mold, a master mold for accommodating the preform, a resin injection section for injecting resin into the master mold, and a product push-up section for pushing up the preform impregnated with resin, and the master mold is detachably provided on the main body.

The mold structure for a high-pressure tank according to the present invention includes a master mold that houses a preform, and a main body having at least a resin injection section and a product push-up section. The master mold that houses the preform is detachably attached to the main body. By replacing only the master mold that corresponds to a preform of a different shape, high-pressure tanks of different shapes can be manufactured with good quality while maintaining the functions of resin injection and resin impregnation required for molding. Furthermore, compared to preparing a molding mold for each shape of preform, the main body having at least a resin injection section and a product push-up section can be reused, thereby achieving low costs. As a result, high-quality high-pressure tanks can be manufactured at low cost.

In the mold structure for a high-pressure tank according to the present invention, the upper mold has built-in piping for vacuum degassing, the main body has an upper body and a lower body that are relatively movable, the upper mold and the lower mold are respectively attached to the upper body and the lower body so that they can be clamped, and the mold structure for a high-pressure tank is preferably further provided with an annular sealing member that is arranged to surround the preform contained in the main mold and seals between the upper body and the lower body and between the upper mold and the lower mold. In this way, the sealing properties of the mold structure can be ensured without being affected by replacement of the main mold, thereby preventing molding defects such as voids.

In the mold structure for a high-pressure tank according to the present invention, it is preferable that the resin injection section has a resin injection pipe provided in the upper body, a resin reservoir section provided in the lower body for storing resin from the resin injection pipe, and a resin extrusion section provided in the lower body for extruding the resin stored in the resin reservoir section toward the main mold. In this way, resin can be injected into the main mold with high precision without being affected by replacement of the main mold. In addition, by temporarily storing the resin in the resin reservoir section and then extruding it toward the main mold rather than injecting it directly into the main mold, fiber shifting of the fiber bundles due to high-pressure resin injection can be prevented.

In addition, in the mold structure for a high-pressure tank according to the present invention, it is preferable that the resin extrusion section has a movable pin that is provided at the bottom of the resin reservoir section and adjusts the depth of the resin reservoir section. In this way, by adjusting the depth of the resin reservoir section with the movable pin, the pressure of the resin injected into the main mold can be controlled, and fiber shifting of the fiber bundle caused by high-pressure resin injection can be prevented.

In addition, in the mold structure for a high-pressure tank according to the present invention, it is preferable that the product push-up section has a push-up member that penetrates the lower mold and pushes up the preform contained in the main mold. In this way, even if the main mold is replaced, the preform impregnated with resin can be accurately removed.

Furthermore, in the mold structure for a high-pressure tank according to the present invention, it is preferable that the upper mold and the lower mold each have a built-in temperature control pipe extending along the longitudinal direction of the preform. In this way, the temperature of the main mold can be stabilized, thereby improving the quality of the manufactured high-pressure tank.

The present invention makes it possible to manufacture high-quality high-pressure tanks at low cost.

FIG. 2 is a schematic vertical cross-sectional view showing a mold structure for a high-pressure tank according to an embodiment. FIG. 2 is a schematic cross-sectional view showing a mold structure for a high-pressure tank according to an embodiment. FIG.

Hereinafter, an embodiment of the mold structure for a high-pressure tank according to the present invention will be described with reference to the drawings. Fig. 1 is a schematic vertical cross-sectional view showing the mold structure for a high-pressure tank according to the embodiment, Fig. 2 is a schematic horizontal cross-sectional view showing the mold structure for a high-pressure tank according to the embodiment, and Fig. 3 is a plan view showing the lower mold and the lower body.

The mold structure 1 for a high-pressure tank in this embodiment is a structure related to an RTM molding mold, and is for manufacturing a high-pressure tank by housing a preform 2, which is an intermediate body of the high-pressure tank, impregnating the fiber bundle of the preform 2 with resin, and further hardening the impregnated resin. The preform 2 is the high-pressure tank before being impregnated with resin, and is formed of a substantially cylindrical liner having a storage space for storing high-pressure gas, and a fiber bundle wound around the outer periphery of the liner. The liner has a cylindrical body portion and a pair of dome portions provided at both axial ends of the body portion.

The fiber bundle is formed by wrapping fibers multiple times around the outer surface of the liner, for example, by the FW method. Examples of the fibers include carbon fiber, glass fiber, and aramid fiber. The resin impregnated into the fiber bundle includes thermosetting resins such as epoxy resin, unsaturated polyester resin, and polyamide resin, but thermoplastic resins such as polyethylene resin and polyester resin can also be used.

The mold structure 1 for a high-pressure tank in this embodiment includes a master mold 10 that houses a preform 2, and a main body 20 that has at least a resin injection section 23 and a product push-up section 24. The master mold 10 is detachably attached to the main body 20.

The master mold 10 has an upper mold 11 and a lower mold 12. The upper mold 11 is detachably attached to an upper body 21, which will be described later, and the lower mold 12 is detachably attached to a lower body 22, which will be described later. The upper body 21 and the lower body 22 are arranged so that they can move relatively in the vertical direction, so that the upper mold 11 and the lower mold 12 can be clamped together. When the upper mold 11 and the lower mold 12 are clamped together, a space (also called a cavity) that contains the preform 2 is formed inside the master mold 10. This space is made larger by, for example, the tolerance of the preform 2.

The upper mold 11 and the lower mold 12 each have built-in temperature control pipes for controlling the temperature of the upper mold 11 and the lower mold 12. Specifically, a plurality of temperature control pipes 13 extending along the longitudinal direction of the preform 2 housed in the main mold 10 (i.e., the axial direction of the preform 2) are arranged inside the upper mold 11. In this embodiment, there are two temperature control pipes 13, which are arranged symmetrically with respect to the axial center of the preform 2. A heater (not shown) is inserted into the temperature control pipes 13, and the upper mold 11 is heated by the heat of the heater. The number of temperature control pipes 13 is not limited to this, and may be increased or decreased as appropriate, taking into consideration the size of the upper mold 11, heating efficiency, etc.

In addition, multiple temperature control pipes 14 are arranged inside the lower mold 12, extending along the longitudinal direction of the preform 2 housed in the main mold 10. In this embodiment, there are two temperature control pipes 14, which are arranged symmetrically about the axial center of the preform 2. A heater (not shown) is inserted into the temperature control pipes 14, and the lower mold 12 is heated by the heat of the heater. Note that the number of temperature control pipes 14 is not limited to this, and may be increased or decreased as appropriate, taking into account the size of the lower mold 12, heating efficiency, etc.

The upper mold 11 also has built-in vacuum degassing piping 15 that extends along the longitudinal direction of the preform 2 housed in the main mold 10. One end of the vacuum degassing piping 15 is connected to the space housing the preform 2, and the other end is connected to a vacuum pump (not shown) arranged outside the mold structure 1 for high-pressure tank. When the vacuum pump is driven, the inside of the main mold 10 (i.e., the space housing the preform 2) can be vacuum degassed via the vacuum degassing piping 15.

The main body 20 further includes an upper body 21 and a lower body 22 that are relatively movable in the vertical direction in addition to the resin injection section 23 and the product push-up section 24 described above. In this embodiment, for example, the lower body 22 is fixed and the upper body 21 is movable (movable relative to the fixed type), but the upper body 21 may be fixed and the lower body 22 may be movable, or both the upper body 21 and the lower body 22 may be movable.

As shown in FIG. 1, the upper body 21 is a frame body formed with a U-shaped cross section so as to have a space for mounting the upper die 11 of the master die 10. The lower body 22 is a frame body formed with a U-shaped cross section so as to have a space for mounting the lower die 12 of the master die 10. The upper body 21 and the lower body 22 are each formed from a metal material, and are arranged in the vertical direction with their U-shaped openings facing each other.

The mold structure 1 for high-pressure tanks also includes a shaft 25 that supports the preform 2. The shaft 25 is formed so that it can be inserted into the nozzles arranged at both the left and right ends of the preform 2, and rotatably supports the preform 2. The shaft 25 also has a hollow structure, and a plurality of through holes are provided in the peripheral wall of the portion that is inserted into the preform 2. In this way, the shaft 25 can also be used as an internal pressure supply member. That is, in order to prevent deformation or damage of the preform 2 due to high-pressure resin injection, it is necessary to inject gas into the liner of the preform 2 to maintain the internal pressure of the preform 2, and by using the shaft 25 having the above-mentioned structure, pressure can be easily supplied to the inside of the liner. The shaft 25 is connected to an internal pressure supply pipe 28. The pressure supply to the liner is not limited to that performed via the shaft 25, and may be performed, for example, via the main mold 10.

The resin injection section 23 has a resin injection pipe 231 provided in the upper body 21, a plurality of resin reservoirs 232 provided in the lower mold 12 for storing resin from the resin injection pipe 231, and a resin extrusion section 233 provided in the lower mold 12 for extruding the resin stored in each resin reservoir 232 toward the main mold 10.

The resin injection pipe 231 is fixed to the upper body 21 in a state where it runs from the upper body 21 to the lower body 22. This resin injection section 23 is connected to a resin storage tank via piping and an opening and closing valve (not shown). The resin storage tank stores a two-part thermosetting resin (e.g., epoxy resin) consisting of, for example, a base resin and a hardener, in a separated state.

As shown in FIG. 3, in this embodiment, there are 16 resin reservoirs 232. Eight of these resin reservoirs 232 are arranged on each side of the axis of the preform 2 contained in the main mold 10. On each side, the eight resin reservoirs 232 are arranged at approximately equal intervals along the longitudinal direction of the preform 2. The resin reservoirs 232 communicate with each other and with the resin injection pipes 231.

As shown in FIG. 1, each resin reservoir 232 is a cylindrical recess having a predetermined depth, and a resin extrusion section 233 is provided at the bottom. The resin extrusion section 233 is provided one-to-one with the resin reservoir 232, and has a cylindrical piston section 233a arranged at the bottom of the resin reservoir 232, and a movable pin 233b connected to the piston section 233a and raising and lowering the piston section 233a with the rotation of the servo motor. When the movable pin 233b rises with the rotation of the servo motor, the piston section 233a also rises, and the depth of the resin reservoir 232 becomes relatively shallow. As a result, the resin stored in the resin reservoir 232 is pushed outward. On the other hand, when the movable pin 233b descends with the rotation of the servo motor, the piston section 233a also descends, and the depth of the resin reservoir 232 becomes relatively deep. By using the movable pin 233b in this way, the depth of the resin reservoir 232 can be adjusted.

Each resin reservoir 232 is connected to the inside of the main mold 10 via a runner 27. As shown in FIG. 3, the runners 27 are provided in a one-to-one correspondence with the resin reservoir 232, and are formed in the lower body 22 and the lower mold 12. The runners 27 are grooves that extend perpendicular to the longitudinal direction of the preform 2 (i.e., in the radial direction of the preform 2), with one end communicating with the inside of the main mold 10 and the other end communicating with the resin reservoir 232. The runners 27 traverse the lower body 22 and the lower mold 12 so as to have a portion formed in the lower body 22 and a portion formed in the lower mold 12.

The reason for providing the resin reservoir 232 will now be explained. That is, when the high-pressure resin is injected into the main mold 10, it may collide with the fiber bundles of the preform 2, resulting in fiber shifting. In order to prevent fiber shifting due to the injection of high-pressure resin, in the mold structure 1 for a high-pressure tank of this embodiment, the high-pressure resin is not injected directly into the inside of the main mold 10, but is instead temporarily stored in the resin reservoir 232, and the stored resin is gradually pushed toward the main mold 10 by a movable pin 233b provided at the bottom of the resin reservoir 232, thereby controlling the pressure of the injected resin.

The product push-up section 24 is provided to push out the preform 2 impregnated with resin, and has two push-up members 241 that penetrate the lower body 22 and the lower die 12 and push up the preform 2 housed in the main die 10, and a lever section 242 that connects the lower ends of the two push-up members 241. The two push-up members 241 each have an elongated shape extending along the longitudinal direction of the preform 2, and are arranged apart so as to be symmetrical with respect to the axis of the preform 2. The upper surface of the push-up members 241 that faces the preform 2 is a curved surface that follows the shape of the outer peripheral surface of the preform 2. In order not to interfere with the replacement of the lower die 12, the push-up member 241 is formed so that the entirety can be lowered and housed in the lower body 22.

When using the product push-up unit 24 having such a structure to push out the resin-impregnated preform 2, for example, in the mold open state, the lever unit 242 is held to push up the push-up member 241, thereby pushing up the preform 2 to a predetermined height.

The mold structure 1 for the high-pressure tank also includes an annular seal member 26 that seals between the upper body 21 and the lower body 22, and between the upper mold 11 and the lower mold 12. As shown in FIG. 3, the seal member 26 is, for example, an O-ring, and is fitted into peripheral grooves (not shown) provided in the lower body 22 and the lower mold 12 so as to surround the preform 2 contained in the main mold 10 and the resin reservoir portion 232.

More specifically, the sealing member 26 has a pair of first portions 261 that are disposed outside the resin reservoir 232 and extend along the longitudinal direction of the preform 2, and a pair of second portions 262 that extend in the radial direction of the preform 2 so as to cross the lower body 22 and the lower mold 12. In this embodiment, the sealing member 26 is a single O-ring, but is not limited thereto, and may be a double structure using, for example, two O-rings of different lengths.

The manufacturing method of the high-pressure tank using the mold structure 1 for the high-pressure tank is briefly described below. The manufacturing method of the high-pressure tank mainly includes a first step of placing the preform 2 inside the main mold 10 and clamping the mold, a second step of injecting resin into the main mold 10 after vacuum degassing, and a third step of hardening the resin and removing the high-pressure tank.

In the first step, first, the master mold 10 corresponding to the preform 2 to be impregnated with resin is attached to the main body 20. For example, master molds 10 corresponding to preforms of different shapes are prepared in advance, and one corresponding to the shape of the preform 2 to be impregnated with resin is selected from among them, and the upper mold 11 is attached and fixed to the upper main body 21, and the lower mold 12 is attached and fixed to the lower main body 22.

Next, the preform 2, which has been prepared in advance, is placed inside the main mold 10. Specifically, with the upper mold 11 attached to the upper body 21 in an open state, the preform 2, which is supported by the shaft 25, is placed in the lower mold 12. Next, heaters are inserted into the temperature control pipes 13 built into the upper mold 11 and the temperature control pipes 14 built into the lower mold 12, and the molds are closed while the upper mold 11 and the lower mold 12 are heated. After closing the molds, the inside of the main mold 10 is vacuum-degassed using the vacuum degassing pipes 15 built into the upper mold 11 and a vacuum pump (not shown).

In the second step, after vacuum degassing is complete, resin is injected into each resin reservoir 232 while pressure is being supplied into the liner of the preform 2. Specifically, gas is supplied into the inside of the liner using the internal pressure supply pipe 28 and the shaft 25. Next, with the piston portion 233a of the resin extrusion portion 233 positioned at the bottom of the resin reservoir 232, the opening and closing valve is opened and the two-component thermosetting resin stored in the resin storage tank is injected into each resin reservoir 232 via the resin injection pipe 231.

Next, while monitoring the pressure condition inside the liner, the movable pin 233b is raised, thereby raising the piston portion 233a, and pushing out the resin stored in the resin reservoir portion 232 towards the main mold 10. The resin then flows into the inside of the main mold 10 via the runner 27 that communicates with the resin reservoir portion 232. This starts the resin impregnation into the fiber bundles of the preform 2. At this time, the rise height of the movable pin 233b is adjusted based on the pressure inside the liner, and the pressure of the resin flowing (in other words, injected) into the inside of the main mold 10 is controlled.

After the resin impregnation is complete, the resin injection is stopped and the resin is cured within the main mold 10. Then, when the resin curing is complete, the mold is opened by raising the upper body 21, and then the product push-up section 24 is used to push up the resin-impregnated and resin-cured preform 2 and remove it from the main mold 10. In this way, the high-pressure tank is manufactured.

The mold structure 1 for a high-pressure tank in this embodiment includes a master mold 10 that contains a preform 2, and a main body 20 that has at least a resin injection section 23 and a product push-up section 24. The master mold 10 is detachably attached to the main body 20. By simply replacing (in other words, exchanging) the master mold 10 that corresponds to a preform 2 of a different shape, high-pressure tanks of different shapes can be manufactured with good quality while maintaining the functions of resin injection and resin impregnation required for molding, and the performance of the manufactured high-pressure tanks can be improved.

In addition, by replacing only the main mold 10 in this way, it is possible to manufacture high-pressure tanks of different shapes, which allows for continuous production and improves productivity. Furthermore, compared to the case where a molding die is prepared for each shape of the preform 2, the main body 20, which has at least the resin injection section 23 and the product push-up section 24, can be reused, which realizes low costs. As a result, high-pressure tanks of high quality can be manufactured at low cost.

In addition, the annular sealing member 26 is provided to surround the resin reservoir 232 and the preform 2 contained in the master mold 10, and seals between the upper body 21 and the lower body 22, and between the upper mold 11 and the lower mold 12. This ensures the sealing of the mold structure 1 for a high-pressure tank without being affected by replacement of the master mold 10, thereby preventing molding defects such as voids.

Furthermore, the resin injection section 23 includes a resin injection pipe 231 provided in the upper body 21, a resin reservoir section 232 provided in the lower body 22 for storing resin from the resin injection pipe 231, and a resin extrusion section 233 provided at the bottom of the resin reservoir section 232 and having a movable pin 233b for adjusting the depth of the resin reservoir section 232. This allows resin to be injected into the main mold 10 with high precision without being affected by replacement of the main mold 10, and prevents fiber shifting of the fiber bundles due to high-pressure resin injection.

The product push-up section 24 has a push-up member 241 that penetrates the lower mold 12 and pushes up the preform 2 contained in the main mold 10, so that the preform 2 impregnated with resin can be accurately removed even if the main mold 10 is replaced. Furthermore, the upper mold 11 and the lower mold 12 of the main mold 10 each have built-in temperature control pipes 13, 14 that extend along the longitudinal direction of the preform 2, so that the temperature of the main mold 10 can be stabilized. This improves the quality of the high-pressure tanks that are manufactured.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-mentioned embodiments, and various design modifications can be made without departing from the spirit of the present invention as described in the claims.

1: High pressure tank mold structure, 2: Preform, 10: Main mold, 11: Upper mold, 12: Lower mold, 13, 14: Temperature control pipe, 15: Vacuum degassing pipe, 20: Main body, 21: Upper body, 22: Lower body, 23: Resin injection section, 24: Product push-up section, 25: Shaft, 26: Sealing member, 27: Runner, 28: Internal pressure supply pipe, 231: Resin injection pipe, 232: Resin reservoir section, 233: Resin push-out section, 233a: Piston section, 233b: Movable pin, 241: Push-up member, 242: Lever section, 261: First section, 262: Second section

Claims (6)

A mold structure for a high-pressure tank for accommodating a preform having a fiber bundle wound around an outer peripheral surface of a liner and impregnating the fiber bundle of the preform with a resin, comprising:
a master mold having an upper mold and a lower mold and accommodating the preform;
a main body having at least a resin injection section for injecting a resin into the master mold and a product push-up section for pushing up the preform impregnated with the resin;
Equipped with
13. A mold structure for a high-pressure tank, wherein the main mold is detachably provided on the main body. The upper mold has built-in piping for vacuum degassing,
The body has an upper body and a lower body that are movable relative to each other,
The upper mold and the lower mold are respectively attached to the upper main body and the lower main body in a mold-clamping manner,
2. The mold structure for a high-pressure tank according to claim 1, further comprising an annular sealing member that is arranged to surround the preform contained in the main mold and that seals between the upper main body and the lower main body, and between the upper mold and the lower mold. The mold structure for a high-pressure tank according to claim 2, wherein the resin injection section includes a resin injection pipe provided in the upper body, a resin reservoir provided in the lower body for storing resin from the resin injection pipe, and a resin extrusion section provided in the lower body for extruding the resin stored in the resin reservoir toward the main mold. The mold structure for a high-pressure tank according to claim 3, wherein the resin extrusion section has a movable pin provided at the bottom of the resin reservoir section to adjust the depth of the resin reservoir section. The mold structure for a high-pressure tank according to claim 1, wherein the product push-up section has a push-up member that penetrates the lower mold and pushes up the preform contained in the main mold. The mold structure for a high-pressure tank according to any one of claims 1 to 5, wherein the upper mold and the lower mold each have built-in temperature control piping that extends along the longitudinal direction of the preform.

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